As known in the field with which the present invention is related to, one of the topics of greatest controversy in contactology is undoubtedly the theme related to the preservation of hydrophilic lenses.
As known, there are two available processes for the treatment of hydrophilic lenses, i. e., the chemical and the thermal.
Asepsis and preservation chemical process uses basically thimerosalt and, as a preservative, the chloroxedine. The advantages relative to this process are related to its efficiency as an antisseptic and to its handling facility. The high cost of the products, however, the development of hypersensitiveness processes with consequent intolerance to the use of lenses and the greatest facility of inorganic impregnation with, for instance, mercury and calcium salts, arise as negative factors limiting its utilization.
Three different stages may be outstanding in this process, thus included: lenses cleaning after use, with an available product, for example, PLIAGEL; preservation with products based on thimerosalt and chloroxedine; disproteinization periodically, with the purpose of making the proteins lysine, having as active agent, the papain. Among the three stages, the disproteinization may be considered the one that presents the best results, inside what it proposes.
However, the thermic process is constituted by two different technics, which are: The hot (by boiling) and the cold (by freezing).
The preservation process by heat is the most used and consists on the direct boiling or in water-bath, in a saline solution or distilled water. Apparently, boiling only presents the advantage of making calcium salts, in the form of carbonate, more soluble, which make difficult its impregnation and difficultates lipids deposition. This process, however, sins by the great risk of damn made to the lenses when realized under direct boiling in a common oven, what does not occur with electric aseptizers. Boiling also promotes the protein cooking, making them more agglutinated and adherent to the villosities of lens surface. We may cite as an example the phenomenon occurring with the white of the egg, basically constituted by albumine, a protein that predominates in the human tear, which on being subjected to cooking, gets firm and opaque, therefore different enough from its initial state. In the case of lenses, proteins also have these transformations and are therefore much more adherent and difficult to be removed when exposed to disproteinization. Boiling also promotes the shortening of the average lenses life, so as to increment polymeric instability.